The present invention relates to ion exchange materials.
Ion exchange materials have been used for purification and demineralization. These materials have a three-dimensional network to which ions are attached. In ion exchange resins, the three-dimensional network is a polymer. In carbon ion exchangers, the three-dimensional network is activated carbon.
Ion exchange resins have been known for almost sixty years (xe2x80x9cIon Exchangersxe2x80x9d; Dorfner, K. (Ann Arbor Science Publishers, Inc. 1972)). The three-dimensional network helps preserve the structural integrity of the material, usually in the form of beads, while the ions provide exchange sites. A large variety of ion exchange resins are described in xe2x80x9cEncyclopedia of Chemical Technologyxe2x80x9d Kirk-Othmer, 3rd ed., vol. 13, pp. 685-93 (1981); and xe2x80x9cIon Exchangersxe2x80x9d ed. Konrad Dorfner, pp. 28-44, and pp. 206-84 (Walter de Gruyter, 1991).
These materials suffer from a number of disadvantages. During the activation of the resin (the stage of attachment of the ions), solvent must be used to pre-swell the cross-linked resin, to reduce the effects of osmotic shock. Furthermore, the beads are very susceptible to fracture and breakage and must be kept wet at all times. Also, pre-swelling prior to service is often required, increasing shipping costs. Finally, there is also a need for ion exchange resins having higher contact efficiencies, speed of regeneration, and longer service life.
Glass or mineral fibers, coated with activated carbon, have been prepared. These materials are described in U.S. Pat. No. 5,834,114. Glass or mineral fibers coated with activated carbon are described as being prepared by coating a glass or mineral fiber substrate with a resin, cross-linking the resin, heating the coated fiber substrate and resin to carbonize the resin, and exposing the coated fiber substrate to an etchant to activate the coated fiber substrate.